The present invention relates to a non-volatile memory device including a non-volatile memory element controlled by a word gate and a select gate.
As an example of a non-volatile memory device, a Metal-Oxide-Nitride-Oxide-Semiconductor or -Substrate (MONOS) type of a non-volatile memory device is known. In the MONOS non-volatile memory device, a gate insulating film between a channel and a gate is formed of a laminate consisting of a silicon oxide film, a silicon nitride film, and a silicon oxide film and a charge is trapped in the silicon nitride film.
As the MONOS non-volatile memory device, a MONOS flash memory cell including a non-volatile memory element (MONOS memory element) controlled by one select gate and one word gate has been disclosed (see Japanese Patent Application Laid-open No. 6-181319, Japanese Patent Application Laid-open No. 11-74389, and U.S. Pat. No. 5,408,115, for example).
In this type of non-volatile memory device, an increase in speed of the read operation has been demanded. In the case where the non-volatile memory device transitions from a standby state to a read state, it is necessary to charge the word gate from 0 V during standby mode mode to a predetermined voltage. However, since the word gate may be formed of poly-silicon or the like, it takes time to charge the word gate. This increases the read cycle time, whereby the speed of the read operation cannot be increased.